Electric apparatus having a



Feb. 14. 1956 A. M. OPSAHL 2,735,040

ELECTRIC APPARATUS HAVING A PROTECTIVE GAP Filed Feb. 8, 195] Flnsullution WITNESSES: INVENTOR 9 qaiyifjgl ATTORNEY United StatesPatent '0 ELECTRIC APPARATUS HAVING A PROTECTIVE GAP Alert M. Opsahl,Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, EastPittsburgh, Pin, a corpora tion of Pennsylvania Application February 8,1951, Serial No. 210,013 Claims. Cl. 317-16 My invention relates toimprovements in electric appa ratus for distribution systems, and it hasreference in particular to a protective gap for reclosing circuitbreakers, sectionalizing switches and such devices as have seriesconnected operating coils.

One object of this invention is to provide in a circuit interrupter ofthe type described, novel means for protecting the coil from lightningand voltage surges from other causes.

Another object of this invention is to provide in a device of the typedescribed a simple and inexpensive protective air gap for protecting theoperating coil thereof.

Another object of the invention is to provide an electric apparatushaving an insulating bushing affording a connection to a series typeoperating coil, for locating a protective air gap for the coil insidethe bushing above the oil level.

These and other objects of this invention will become more apparent uponconsideration of the following detailed description of a preferredembodiment thereof, when taken in connection with the accompanyingdrawing, in which Figure l is a substantially central vertical sectionof a sectionalizing switch constructed in accordance with this inventionand Figure 2 is an enlarged vertical sectional view, broken out in part,of the contact rod assembly used in the insulating bushing shown in Fig.1.

In order to illustrate one embodiment of my invention I have shown it asapplied to a sectionalizer of the type described in detail in copendingapplication Serial No. 106,886 of James M. Wallace and Andrew W.Edwards, which sectionalizer is disposed to be used in conjunction withan automatic reclosing circuit breaker for opening after a predeterminednumber of breaker openings, so as to disconnect a faulty line sectionand permit the breaker to reclose and stay closed. However, it is to beunderstood that my invention is not intended to be limited to thistype-of circuit interrupters, but may be used with reclosing breakersand other types of electrical apparatus also.

Referring to Fig. 1 it will be seen that a sectionalizer 17 is shown asbeing enclosed within a metal tank 27, which is provided with aninsulating liner 28, and which is surmounted by a top casting 29. Anincoming line 15 enters through a bushing 31 which terminates inside ofthe tank. The circuit then continues, through a conductor 32, to thesectionalizer coil 19. From the sectionalizer coil 19, the circuitcontinues through a conductor 33 back under neath the bushing 31 for theincoming lead 15, and thence to the terminal 3 which constitutes one ofthe stationary contacts of the sectionalizer. Ordinarily, thesectionalizer has two bushings, each with its lead passing through thebushing, and each bushing terminates at its bottom in, or supports atits bottom, one of the stationary contacts of the sectionalizer, butsince Fig. 1 shows an approximate central vertical section through thesectionalizer,

the second stationary contact is not visible in Fig. 2. The movablecontact 20 is shown, in Fig. 1, as a contact bar or bridge which pressesup against the underside of the stationary contact 34 and the otherstationary contact (not shown) in the closed position of thesectionalizer, and which is lowered by gravity, to operate thesectionalizer, upon the release of a pull rod 36, which is shown in theform of an upwardly extending insulating tube.

A counter and lockout mechanism 23 is segregated, in Fig. 1, into itscomponent parts, consisting of the counter 37 and the operatingmechanism 38.

The sectionalizer 17 can theoretically operate either in air, or in aninsulating oil or other insulating fluid. It is sometimes desirable forthe counter 37 to operate in oil, as it involves dashpot or fluid flowoperation, as subsequently described, which is somewhat more diflicultto obtain in air, with the necessary time constants. It is sometimesdesirable to have the contacts 34-20 also operating in oil. We haveconsequently illustrated our apparatus, by way of example, as having thecounter 37 and the contacts 3420 immersed in oil 40 which is containedin the tank 27.

The particular operating mechanism 38 which is shown in the accompanyingdrawing constitutes the subject matter of application Serial No. 106,887of J. M. Wallace and A. W. Ogg. In brief, it will perhaps sufiice to saythat this operating mechanism comprises a bell-crank trigger 53 and anoperating handle 69. The trigger 53 supports a lever 47 which ispivotally mounted by a pivot 43 on a frame 41 secured to the casting 29.A lever 43 is pivotally mounted on the lever 47, and the rod 36 ispivotally secured to one point of the lever 43, which is generallytriangular. A lever 46 which is connected in toggle arrangement with ahandle 66 mounted on the casting 29 by a pivot 61, is pivotallyconnected to the third point on the lever 43. The trigger 53 has adownwardly extending abutment-portion 56 which is adapted to be trippedwhen an upward movement of a trip pin 57 of the counter 37 raises saidabutment point 56 of the trigger, whereupon the linkage of the operatingmechanism permits the pull rod 36 and the movable-contact member 20 todrop freely in the opening operation of the mechanism.

The counter 37, which is described in detail and claimed in thecopending application Serial No. 106,886 of J. M. Wallace and A. W.Edwards, is suspended from the top of the top casting 29, by means of aplurality of depending insulating supports or tubes 70, which supportthe base frame 71 of the counter. The counter proper 37 comprises avertically disposed tube 72, which is preferably made of brass'or othernon-magnetizable metal. The lower end of the tube is tightly closed by aplug 73, while the top of the tube 72 is open. The series current coil19 surrounds a portion of the tube 72, intermediate its upper and lowerends. Immediately above and below the coil 19 are two perforatedmagnetizable plates 74 and 75, respectively, both of which areperforated so as to surround the tube 72. The plates 74 and 75 serve asthe two pole pieces of an electromagnetic circuit, the excitation ofwhich is provided by the coil 19.

Inside of the tube 72 are two normally spaced magnetizable cores orarmatures 76 and 77, which are slidably movable, with a close fit of sayperhaps 3 mils radial clearance, within said tube. The upper armature 76extends partly above and partly below the level of the upper plate 74,while the lower armature 77 extends partly above and partly below thelower plate 75. Each of these armatures 76 and 77 thus extends partlywithin and partly without the space between the two plates 74 and 75.

At least one of the armatures, such as the upperarmature 76, andpreferably both of the armatures 76 and 77, are provided with aplurality of annular magnetizable ribs 78 which are vertically spacedfrom each other by a spacing which is preferably approximately the samedistance as the closable distance between the two armatures 76 and 77,or other disposition which will magnetically lock the respectivearmatures against unwanted vertical displacement or slippage. Acompression spring 79 is disposed between these two armatures, so that,when the coil 19 is sufliciently energized, the two armatures arebrought together, storing up energy in the interposed compression-spring79, as will be more fully described hereafter.

Each of these armatures 76 and 77 is provided with a central bore, thelower end of which is closable by means of a ball valve 82 so that thefluid which is entrapped within the closed lower end of the tube '72resists any rapid downward movement of either armature, be cause of theclosure of these ball valves, while said valves permit the free upwardmovement of either armature. The entrapped fluid could be any gas orliquid having the required viscosity in comparison with the mechanicalclearances which are provided. The idea is to permit the respectivearmatures to move freely upwardly, in a step by step motion, as will besubsequently described, while permitting said armatures to drift backdownwardly again, by fluid leakage, at a very slow rate.

At the top of the upper armature 76 is a tubular tip or trip pin 57,which is capable of actuating the trigger 53 after any desired number ofcounts, such as 1, 2, 3 or 4, within the range of the counting mechanism37.

In the operation of the counting mechanism 37, when the coil 19 is firstenergized, with a current corresponding to the setting of the counter,the two armatures 76 and 77 are drawn together, so as to close the airgap which separates the inner ends of said armatures. The upper armature76 cannot move downwardly to bring the two armatures together, becauseof the presence of its fluid flow valve, and hence the lower armature 77must move upwardly. The attractive force between the two armatures isgreater than the attractive force between the lower plate 75 and thecorresponding rib 78 of the lower armature 77, which was at first on thesame level as said lower plate 75. When the lower armature completes itsupward movement, compressing the spring 79, its next rib 78 comes into amagnetic interlock with the lower plate 75, thus holding said lowerarmature from drifting or settling downward, due to gravity and the slowleakage of the fluid filling of the tube 72.

When there is a fault on the distribution line, within the protectivereach of the recloser associated with the sectionalizer, the reclosercontact quickly opens, and quickly again recloses, but during the moment(12 cycles or more, in a 60-cycle line) when said recloser contact wasopen, the sectionalizer coil 19 is deenergized, and the compressionspring 79 between the two armatures 76 and 77 expands, and pushes thetwo armatures apart again, to their normal separation distance. Duringthis action, however, the lower armature 77 cannot move downwardly,because of its fluid flow valve, and hence the upper armature 76 mustmove upwardly, which it is free to do, so far as fluid action isconcerned, because its valve will open during such movement. Themagnetic attraction between the upper and lower plates 74 and 75 and thecorresponding magnetizable ribs 78 of the upper and lower armatures 76and 77 is now practically nonexistent, because of the deenergization ofthe coil 19, and hence the upper armature 76 is notched upwardly by adistance corresponding to the amount of compression of the spring 79.

If a fault continues on the distribution system, at a point beyond thesectionalizer coil 19, the reclosure of the recloser contact reenergizesthe sectionalizer coil 19 and causes a second compression of the spring79, in a manner already described. If the fault is still on the system,as has just been assumed, the recloser contact again opens, and a secondupward stepping movement of the trip pin 57 is obtained. And thus thestep by step movement of the counter mechanism continues.

When the last upward stepping of the upper armature 76 is obtained,depending upon the vertical positioning of the trip pin or tubular tip57, this pin 57 comes into contact with the trigger 53 during this lastupward move ment, and trips out the sectionalizer contact 20. It will benoted that this last upward movement of the trip pin 57 occurs during atime when the current in the sectionalizer coil 19 is off. In theoperation of a reclosing circuit breaker the current remains ofi, thatis, the recloser contact remains open, for a minimum of l2 cycles (on a60-cycle line), before the recloser contact recloses. The opening of thesectionalizer contact 20 requires something like 2 or 3 cycles, so thatit is seen that the sectionalizer contact 20 opens during the currentott period, so that the sectionalizer contact 20 does not have tointerrupt any substantial current.

In order to protect the sectionalizer coil 19 from volt age surges suchas caused by lightning and the like, it is desirable to use a protectivegap to permit such surges to bypass the coil. Becausea gap in oilrequires such a close spacing for it to be effective that it makes sucha gap difiicult to calibrate and maintain, an air gap is more desirable.Instead of providing a separate gap device as has been used heretofore,I propose to build the gap integrally with the bushing 15, whereby asimple and inexpensive, as well as durable and reliable air gapstructure is provided.

Referring to Figs. 1 and 2 it will be seen that the conductor 15 maycomprise a rod 80 threaded at its upper end to receive a suitableterminal connection. A threaded portion 31 may be provided adjacent thelower end of the rod 81 to receive a tubular conductor 84. The tubularconductor may be provided with a shoulder 83 adjacent its lower end, bymeans of a bushing 85 which may be brazed or otherwise secured in theconductor together with a connector terminal 86. A central electrode rod87 may be positioned in the conductor 84 by means of an insulatingbushing 89, being located by means of a snap ring 90 and a nut 92 on rod87. An insulating washer 93 separates the nut 92 from the end of tubularconductor 84. A contact 34 and a connector terminal 95 may be secured onthe lower end of the electrode 37. An annular gap 96 will thus beprovided between the upper end of the electrode 87 where it projectsbeyond the bushing 89 and the inner Wall of the conductor 84, which isconnected in shunt circuit relation with the coil 19 by conductors 32and 33. Any voltage surge appearing across the coil 19 will thus bebypassed around the coil across the gap.

By utilizing a protective gap in the manner hcreinbefore described, apositive and reliable air gap is provided for protecting the series coilagainst voltage surges such as may be caused by lightning or switchingsurges. The gap integral with the insulating bushing makes a compact andefficient structure requiring fewer parts and making a less expensiveassembly. The gap is so located that its calibration is unaffected bythe presence of oil in the tank, yet all parts of the gap are adequatelyinsulated from ground.

Since certain changes may be made in the above described construction,and different embodiments of the invention may be made without departingfrom the spirit or scope thereof, it is intended that all the mattercontained in the above description and shown in the accompanying drawingshall be considered as illustrative and not in a limiting sense.

I claim as my invention:

1. A circuit interrupter comprising a metal casing, a stationary contactand a cooperating movable contact in said casing, electro-responsivemeans in said casing eleetrically'connected in series circuit relationwith said contacts and operable in response to predetermined abnormalcOnditiOns in the circuit to effect movement of said movable contact toan open circuit position to interrupt the circuit, said contacts andelectro-responsive means being electrically insulated from said casing,a hotlow insulating bushing extending through a Wall of said easing intothe interior thereof, a conductor extending into said bushing fromoutside said casing and electrically connected in series circuitrelation with said electro-responsive means and said contacts, a secondconductor coaxially disposed in predetermined spaced relation with theaforesaid conductor in said bushing to provide a protective gaptherebetween completely enclosed by said bushing and insulated from saidcasing for protecting said electro-responsive means from predeterminedabnormal voltage conditions, said second conductor being electricallyconnected to said stationary contact and to said electroresponsive meansso that said gap is electrically connected in shunt relation to saidelectro-responsive means, said stationary contact being supported fromsaid insulating bushing.

2. In combination, electrical apparatus having electroresponsive meansoperable to etfect operation thereof, a metal casing for enclosing saidelectrical apparatus, said apparatus and electro-responsive means beingmounted within said casing and insulated therefrom, a hollow insulatingbushing extending through said casing into the interior thereof andhaving an electrical conductor means extending from outside said casinginto said bushing and insulated from the casing thereby, an additionalconductor coaxially disposed in spaced relation with the aforesaidconductor means within said bushing to provide a gap therebetweencompletely enclosed by the bushing, said additional conductor beingelectrically connected to the electrical apparatus, and circuit meanselectrically connecting said conductor means to one terminal of theelectro-responsive means and said additional conductor to the otherterminal of said electro-responsive means to provide a single protectivegap within the bushing with both said conductor means and additionalconductor insulated from the metal casing by the bushing and said singlegap disposed directly in shunt circuit relation with saidelectro-responsive means.

3. A circuit interrupter comprising, a metal container having aninsulating fluid therein, a metal cover for said container, a pair ofstationary contacts disposed in the fluid, support means for saidcontacts including a conductor extending through the cover, supportmeans for said conductor comprising an insulating bushing disposed aboutthe conductor and extending through the cover into the fluid, a movablecontact normally disposed in bridging relation With said stationarycontacts, trip means including an electromagnetic device electricallyconnected in series circuit relation with said contacts operable inresponse to predetermined conditions in the circuit for effectingseparation of the movable contact from the stationary contacts, and anadditional conductor disposed in said bushing between said firstmentioned conductor and the stationary contact, said additionalconductor being supported by said bushing and electrically connected toone of said stationary contacts and disposed in spaced end to endrelation with said first mentioned conductor, said first mentionedconductor including a tubular extension secured thereto and extendingabout a portion of the additional conductor to provide a predeterminedradial air gap therebetween above the fluid and remote from the cover,and rigid connectors extending radially from the first mentionedconductor and additional conductor connecting said conductors and theelectromagnetic device to place the electromagnetic device in serieswith the contacts and the gap in shunt circuit relation with theelectromagnetic device.

4. A circuit interrupter comprising, a metallic container, a metal coverfor said container, separable contacts disposed in said container,electro-responsive means having a solenoid electrically connected inseries with said contacts operable in response to predetermined overloadconditions to effect separation of said contacts, said contacts andelectro-responsive means including said solenoid being electricallyinsulated from said metallic container and cover, an insulating bushingextending through said cover into a central portion of the containerhaving a conductor therein connected in circuit relation With saidcontacts and solenoid, electrode means carrying one of said contactsdisposed in coaxial and spaced relation with said conductor in saidbushing and supported by the bushing in the central portion of thecontainer, said conductor including a hollow extension extending about aportion of said electrode means and in predetermined spaced relationtherewith to provide a protective gap within said bushing to protectsaid solenoid of the electro-responsive means from excessive voltagesurges, and rigid connectors electrically connecting said hollowextension of said conductor to one terminal of said solenoid andelectrically connecting said electrode means to the other terminal ofsaid solenoid so that said protective gap is in shunt relation to saidsolenoid.

5. In a protective device for a circuit interrupter having a metalcontainer, separable contacts disposed in said container, andelectro-responsive means having a solenoid connected in series circuitrelationship with said contacts disposed in said container operable inresponse to predetermined overload conditions to effect separation ofsaid contacts; said contacts and electro-responsive means beingelectrically insulated from said metal container, an insulating bushingextending into a central portion of said container provided with aconductor therein disposed to be connected in series circuit relationwith said solenoid of the electro-responsive means and said contacts,said conductor having a hollow portion Within said insulating bushing insaid central portion of the container with oppositely disposed openingstherein, an electrode disposed within the hollow portion of saidconductor connected to and supporting one of said contacts and having anend adjacent said openings, insulating means supporting said electrodein predetermined spaced relation with said conductor to provide aprotective air gap therebetween, and rigid radial connectors on theelectrode and hollow portion connecting the electrode in said seriescircuit relation with the solenoid of the electro-responsive means as toconnect the gap in shunt relation therewith.

References Cited in the file of this patent UNITED STATES PATENTS656,680 Thomson Aug. 28, 1900 1,310,054 Brown July 15, 1919 1,472,346Kline July 17, 1923 2,142,188 Gaston Jan. 3, 1939 2,242,838 Somes May20, 1941 2,250,165 Mitschrich July 22, 1941 2,281,073 Leonard Apr. 28,1942 2,333,604 Wallace Nov. 2, 1943 2,414,786 Luicks et al. Jan. 21,1947 2,464,303 Gesellschap Mar. 15, 1949 2,567,413 Van Ryan et al. Sept.11, 1951

